<template>
  <div class="city_body">
    <div class="city_list">
      <div class="city_hot">
        <h2>热门城市</h2>
        <ul class="clearfix">
          <li v-for="item in hostCity" :key="item.id">{{ item.nm }}</li>
        </ul>
      </div>
      <div class="city_sort" ref="city_sort">
        <div v-for="item in cityData" :key="item.id">
          <h2>{{ item.index }}</h2>
          <ul>
            <li v-for=" list  in item.list" :key="list.id">{{ list.nm }}</li>
          </ul>
        </div>
      </div>
    </div>
    <div class="city_index">
      <ul>
        <li v-for="(item,index) in cityData" :key ="item.id" @click="toTarget(index)">{{ item.index }}</li>
      </ul>
    </div>
  </div>
</template>

<script>
export default {
  name:'cityList',
  data: function() {
    return {
      cityData: [],
      hostCity: []
    };
  },
  mounted() {
    // 获取数据
    this.axios.get("/api/cityList").then(res => {
      // console.log(res.data.data)
      var data = res.data.data.cities
      // 对数据进行处理
      this.cityData = this.formatCityList(data)
      this.hostCity = this.chooseHotCity(data)

    });
  },
  methods: {
    // 对单词首字母进行
    formatCityList(cities) {
      // 检查数据是否传入
      // console.log(cities)
      // 这里可以作出一个判断？ 判断数据是否正确传入
      var cityList = [];
      // var hostList = [];
      // 循环遍历传递过来的数据
      for (var i = 0; i < cities.length; i++) {
        // 取出数组中每个单词的字母
        var firstLetter = cities[i].py.substring(0, 1).toUpperCase();
        if (toCom()) {
          cityList.push({
            index: firstLetter,
            list: [{ nm: cities[i].nm, id: cities[i].id }]
          });
        } else {
          // 累加到已有索引
          for (var j = 0; j < cityList.length; j++) {
            if (cityList[j].index === firstLetter) {
              cityList[j].list.push({ nm: cities[i].nm, id: cities[i].id });
            }
          }
        }
      }
      // 处理排序
      cityList.sort(function(a, b) {
        if (a.index > b.index) {
          return 1;
        } else if (a.index < b.index) {
          return -1;
        } else {
          return 0;
        }
      });

      //在写一个判断的函数
      function toCom() {
        for (var i = 0; i < cityList.length; i++) {
          if (cityList[i].index === firstLetter) {
            return false;
          }
        }
        return true;
      }
      // console.log(cityList)
      return cityList;
    },
    // 选出热门城市
    chooseHotCity(cities){
      let hostCity = []
      for (var i = 0; i< cities.length; i++){
        if (cities[i].isHot === 1){
          hostCity.push(cities[i])
        }
      }
      return hostCity
    },
    // 点击字母进行跳转 
    toTarget(index){
      // console.log(index)
      // 处理dom 
      let h2 = this.$refs.city_sort.getElementsByTagName('h2')
      // console.log(h2)
      // console.log(this.$refs.city_sort.parentNode.scrollTop)
      // 给父级的scrollTop 设置为 当前h2的卷曲出去的高度
      this.$refs.city_sort.parentNode.scrollTop = h2[index].offsetTop
    }
  }
};
</script>

<style lang="scss" scoped>
.clearfix {
  overflow: hidden;
}
.city_body {
  margin-top: 80px;
  margin-bottom: 60px;
  display: flex;
  width: 100%;
  position: absolute;
  top: 0;
  bottom: 0;
}
.city_body .city_list {
  flex: 1;
  overflow: auto;
  background: #fff5f0;
}
.city_body .city_list::-webkit-scrollbar {
  background-color: transparent;
  width: 0;
}
.city_body .city_hot {
  margin-top: 20px;
}
.city_body .city_hot h2 {
  padding-left: 15px;
  line-height: 30px;
  font-size: 14px;
  background: #f0f0f0;
  font-weight: normal;
}

.city_body .city_hot ul li {
  float: left;
  background: #fff;
  width: 29%;
  height: 33px;
  margin-top: 15px;
  margin-left: 3%;
  padding: 0 4px;
  border: 1px solid #e6e6e6;
  border-radius: 3px;
  line-height: 33px;
  text-align: center;
  box-sizing: border-box;
}
.city_body .city_sort div {
  margin-top: 20px;
}
.city_body .city_sort h2 {
  padding-left: 15px;
  line-height: 30px;
  font-size: 14px;
  background: #f0f0f0;
  font-weight: normal;
}
.city_body .city_sort ul {
  padding-left: 10px;
  margin-top: 10px;
}
.city_body .city_sort ul li {
  line-height: 30px;
  line-height: 30px;
}
.city_body .city_index {
  width: 20px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-align: center;
  border-left: 1px #e6e6e6 solid;
  li{
    margin: 7px 0;
  }
}
</style>
